In my thesis I focus on diagnosing school maturity of children and finding out possibilities of its development. In theoretical part I describe pre-school period as such, then I focus on pre- schools involved in the "Beginning together" program. Furthermore, I explain characteristics of school maturity and ways how to develop them, and finally I address Pedagogic - psychological diagnostics of school maturity. In practical part I researched into how pre- schools with the "Beginning together" program work with pre-school children and children with delayed school entry, I also researched if this program has any special procedures for development of school maturity.